Mechanism for clamping flexible printing plates



N. NORLIN Sept. 5, 1961 3 Sheets-Sheet 1 Filed Dec. 22, 1958 w 1%. m w mM Q Q? m Q1 E L r :E MT L 37/ L R Q .r \s 4 @FQIwQEk w w Q wmi Q Q I m TE Ts Z L ow :J 5 x ,Q N u Q wv HR w M w. a TIM. Q Q m T T w fiwi w s, dhqit hi4 Attorneys Sept. 5, 1961 N. NORLIN 2,998,768

MECHANISM FOR CLAMPING FLEXIBLE PRINTING PLATES Filed Dec. 22, 1958 3Sheets-Sheet 2 -v iii 4 t Y W5) 1% Sept. 5, 1961 NORLIN 2,998,768

MECHANISM FOR CLAMPING FLEXIBLE PRINTING PLATES Filed Dec. 22, 1958 3Sheets-Sheet I5 F/GG.

Inventor: )7% 770423 A8 Attorneys United States Patent 2,998,768MECHANISM FOR CLAMPING FLEXIBLE PRINTING PLATES Nils Norlin,Halsingborg, Sweden, assignor to Carl Allen's Etablissement A/ S,Copenhagen, Denmark Filed Dec. 22, 1958, Ser. No. 782,188 12 Claims.(Cl. 101-4151) This invention relates to mechanism for securing aflexible printing plate to the plate dylinder of a printing machine,especially, but not exclusively, an offset printing machine.

Various proposals have already been made [for that purpose and accordingto certain of the proposals the ends of the plate are bent, or areprovided with extensions, to pass into an axial groove or gapdormed inthe periphery of the cylinder. clamping bars which are formed withgrooves to receive turned-out flanges or lips at the inner ends of theplate. The gap accommodates some mechanism or another to move the barsmore or less tangentially in the gap to pull the plate and to secure ittightly to the cylinder.

It has been found that on account of the force which has to be appliedto the plate ends, there is a tendency for the lips to become embeddedin the grooves in the bars when the mechanism is operated torelease theplate. The gap between the bars and the bent down ends of the plate ismade as small as possible to avoid interrupting the continuity of theprinting surface for more than is necessary. The gap, being thusdesirably small, renders it difiioult if not impossible to gain accessto the embedded end of the plate with the result that time is wasted andthe plate even damaged in attempting to dislodge the lip.

It is the main purpose or this invention to provide a mechanism whichwill avoid this difficulty.

According to the present invention the plate clamping mechanism isarranged so as, when operated to release a plate, to apply a strippingaction to the lips so as forcibly to remove them from the grooves in thebars.

The invention can be carried into efiect in various ways, In aconvenient arrangement the bars are formed in two parts which define thelip-receiving groove between them. The operating mechanism for the barsis arranged so that, when it is operated to release a plate, it efiectsrelative movement between the two parts of .the bar and so ensures thatthe lips are dislodged. This mechanism. is of a type which is operableirom outside the groove, and so the d-ifliculty of releasing an embeddedlip no longer applies.

The invention is illustrated in one form of construction in theaccompanying drawings, in which: FIGURE 1 is a longitudinal sectionalelevation taken through the usual gap formed in a printing cylinder;FIGURE 2 is a sectional plan view, the section being taken on the lineIll-11, FIGURE 1, FIGURES 3, 4, and 6 are sectional elevations takenrespectively on the lines III- 111, IV--IV and V--V and VI--VI in FIGURE1, and FIG- URE 7 is a sectional detail view.

Referring to the drawings, a part of the body of the printing cylinderof a printing machine is indicated at 1, this cylinder requiring to havea printing plate 2 wrapped about its periphery, as shown in FIGURES 3-6.Such a plate is commonly of metal. The cylinder is formed in itsperiphery with an axially extending groove 3 in which is held a unit 4carrying clamping bars 5 and a mechanism for moving those bars towardsand away from one another.

The ends of the plate 2 are bent down at 6 to-pass into the gap betweenthe clamping bars 5, and the extreme inner ends of the plate are bentout to provide lips 7 In that gapare disposed i r o ce 2 x for attachingthe plate to the bars. The lips 7 extend into grooves 8 formed in theclamping bars 5 so that movement of the bars 5 towards one another willre sult in a pull being applied to the ends of the plate via the lips 7.The radially outermost walls of the grooves 8 and the lips 7 act asradially interlocking parts engageable with each other for restrainingthe plate end portions 6 against outward movement radially with respectto the cylinder 1.

It is the purpose of'this invention to ensure that when the bars 5 areoperated for the purpose of releasing the plate, the lips 7 shall notremain embedded in the grooves 8. To achieve this result the recesses 8are formed 'conjointly by the walls of recesses in the main barparts 5and by the outer surfaces of shoulders 9' on supplementary parts 9. Theends of the shoulders are formed either locally or continuously withupstand-i ing portions or beads 10 against which the ends of the lips 7on the plate abut.

Thus by. moving the supplementary parts 9 in the lengths of the recesses8 relative to the main clamping bar part 5 during the plate releasingoperation, the beads press against the ends of the lips 7 to eject themfrom the grooves 8.

The particular clamping mechanism shown in the drawing comprises aseries of pins 1 1 disposed in and along the length of the groove andwithin the circumference of the cylinder '1. These pins have betweentheir ends operating discs 12 which extend out into the gap between thebent down parts 6 of the plate. The parts 13 of the pins at each side ofthe discs are cylindrical to turn in openings in the supplementary parts9 and in openings in the main bar parts 5. The ends of the cylindricalparts of the pins marked generically A in FIGURE 4 react against parts14 in the walls of the unit 4 so that the pins are held against axialmovement. The pins A have the cylindrical surfaces at one side of thediscs screw threaded as shown at 15 in FIGURE 4, and others of the pinsA at the other side of the discs are similarly screw threaded (seeFIGURE 2). Thus, by turning the pins at the dilierent points along thelength of the main bars 5, the latter can be moved towards and away fromone another and skewed to one another as may be required.

In addition, certain of the pins marked generically at B and shown inFIGURE 3 are not onlyscrewed into one or other of the main bar parts 5,but are also pro vided with outstanding flanges 16 to engage behind theends to cooperate with corresponding races on the side shoulders 9 onthe supplementary parts 9. Thus the purpose of the invention is servedfor when these pins B (which are oppositely disposed as seen in FIGURE2. to operate respectively the two supplementary bars 9) are turned theymove axially with respect to the main parts 5, and their flanges 16press against the shoulders 9 of the supplementary parts 9 which arethus moved in predetermined paths from retracted positions to oper-'ated positions whereby their beads 10 strip the lips 7 from the groove8. 7

As is shown in FIGURE 7 each flange 16 can be constituted by a 0 ringwhich is sprung into a circumferential recess in the related pin 11.

The supplementary parts 9 also have upstanding flanges 17 which trap thelower ends of the downturned flanges 6 of the plate 2 between the parts5 and 9 when the supplementary parts 9 are moved toward the associatedmain bar parts 5.

The main bar parts are sloped at 18 at their outer walls of the unit 4.

Further pins marked generically at C and shown in detail in FIGURE 6 canalso be provided. These pins have cylindrical parts 11 which however arenot screw Patented Sept. 5, 1961 3 threaded, but merely turn in openingsin the main and supplementary bar parts and 9, the ends of these pinshaving eccentric stubs 19 engaging in slippers mounted in slots .21 inthe side walls of the unit 4. These pins C enable the bent down ends ofthe plate to be drawn' radially into the groove.

The clamping mechanism described thus enables, by manipulation of thevarious pins A and C, the control of the tensioning and setting of theplate 2 on the cylinder 1 to obtain proper registration in the printingoperation. By the manipulation of the pins B the plates can readily beejected from the groove in the clamping bars 5 and supplementary parts 9by which they had been tensioned.

I claim:

1. In a printing cylinder construction, a cylinder formed at its outersurface with a groove extending parallel to the cylinder axis forreceiving the end portions of a flexible printing plate wrapped aroundsaid cylinder, which end portions are turned inwardly to extend intosaid groove and are formed at their extreme ends with lips extendingoppositely and away from each other; two clamping bar structures mountedin said groove respectively between said plate end portions and thegroove walls and having recesses for receiving said lips; ejecting meansmounted within said groove for movements in predetermined paths fromretracted positions to operated positions in engagement with said lipsfor ejecting the latter from said recesses; and operating means mountedin said groove within the circumference of said cylinder and beingoperable in said groove for moving said bar structures relatively toeach other and to the groove walls for tensioning the plate about thecylinder and for moving said ejecting means to operated positions.

2. In a printing cylinder construction, a cylinder formed at its outersurface with a groove extending parallel to the cylinder axis forreceiving the end portions of a. flexible printing plate wrapped aroundsaid cylinder, which end port-ions are turned inwardly to extend intosaid groove and are formed at their extreme ends with lips extendingoppositely and away from each other; two clamping bar structures mountedin said groove respectively between plate end portions and the groovewalls and having recesses for receiving said lips; operating means formoving said bar structures relatively to each other and to the groovewalls for selectively tensioning the plate about the cylinder and forrelieving the tension on the plate; and means operable for ejecting saidlips from said recesses when said bar structures have been moved torelieve the tension on said plate.

3. Printing cylinder construction according to claim 2 in which each ofsaid bar structures comprises a main clamping bar part and asupplementary her part contiguous thereto, said main and supplementarybar parts being formed conjointly to define between them the lipreceiving recess.

4. Printing cylinder construction according to claim 3 including meansfor moving said main clamping bar and supplementary bar parts relativelyto one another, said last mentioned means comprising a plurality of pinseach journaled to rotate freely in one of said bar structures and in thesupplementary bar part of the other of said bar structures, a threadedportion of said pin engaging a threaded opening in the main bar part ofsaid other of said bar structures, said pin having means thereon formoving the supplementary bar part of said other of said structuresaxially of said pin in response to axial movement of said pin relativeto the main bar part or said other of said structures.

5. Printing cylinder construction according to claim 3 in which one ofsaid bar parts defines one wall of the recess and has an upstandingportion defining the outer end of the recess, in which the bar parts ofeach of said bar structures are relatively movable, and in which saidupstanding portion of said one of said bar parts is engageable with theedge of the associated plate lip for 4 urging the lip out of the recesswhen said bar parts are moved relatively.

6. Printing cylinder construction according to claim 3 in which saidoperating means comprises a first series of components disposed atintervals along the length of the groove for moving the two barstructures away from and toward one another to tension and release saidplate, said means for ejecting the plate lips from the recess when saidbar structures are moved toward each other to release said platecomprising a second series of components disposed at intervals along thelength of said groove.

7. Printing cylinder construction according to claim 6 in which saidfirst and second series of components are individually operablerespectively for moving said bar structures away from and toward oneanother to tension and release said plate, and for moving the mainclamping bar and supplementary clamping bar parts relatively to oneanother to eject the plate lip from the recess conjoint-1y defined bysaid bar parts.

8. Printing cylinder construction according to claim 7 in which one ofsaid bar structures is formed with openings and the other of said barstructures is formed with threaded openings, and in which each ofcertain of said components comprises a rotatable pin extending acrossthe cylinder groove and having a disc portion on the pin between theends thereof, the pin having on one side of the disc portion acylindrical end rotatably received in one of the openings in said one ofsaid bar structures, and the pin having on the opposite side of the discportion a screw portion engaging one of the threaded openings in saidother of said bar structures.

9. Printing cylinder construction according to claim 8 in which said oneof said bar structures is also formed with threaded openings and saidother of said bar structures is also formed with further openings, andin which others of said components comprise other pins formed similarlyto the first mentioned pins but which are reversely disposed withrespect to the latter, said others of said pins having their cylindricalends rotatably received in said further openings in said other of saidbar structures and their screw portions engaging said threaded openingsin said one of said bar structures.

10. Printing cylinder construction according to claim 8 including stillfurther pins spaced along said bar structures andbeing rotatabletherein, said further pins having eccentric portions journaled in saidcylinder whereby rotation of said further pins will draw said barstructures radially into said groove.

11. In a printing cylinder construction, a cylinder formed at its outersurface with a groove extending parallel to the cylinder axis forreceiving the end portions of a flexible printing plate wrapped aroundsaid cylinder, which end portions are turned inwardly to extend intosaid groove and are formed with first radially interlocking parts; twoclamping bar structures mounted in said groove respectively between saidplate end portions and the groove walls and having second radiallyinterlocking parts cooperable with said first radially interlockingparts for restraining said plate end portions against outward movementradially of said cylinder; ejecting means mounted within said groove formovements in predetermined paths from retracted positions to operatedpositions in engagement with said first radially interlocking parts fordisengaging the latter from said second interlocking parts; andoperating means mounted in said groove within the circumference of saidcylinder and being operable in said groove for moving said barstructures relatively to each other and to the groove walls fortensioning the plate about the cylinder and for moving said ejectingmeans to operated positions.

1-2. In a printing cylinder construction, a cylinder formed at its outersurface with a groove extending parallel to the cylinder axis forreceiving the end portions of a flexible printing plate wrapped aroundsaid cylinder,

5 which end portions are turned inwardly to extend into said groove andare formed with first radially interlocking parts; two clamping barstructures mounted in said groove respectively between said plate endportions and the groove walls and having second radially interlockingparts cooperable with said first radially interlocking parts forrestraining said plate end portions against outward movement radially ofsaid cylinder; ejecting means mounted within said groove for movementsin predetermined paths from retracted positions to operated positions inengagement with said first radially interlocking parts for disengagingthe latter from said second interlocking parts; and operating meansmounted in said References Cited in the file of this patent UNITEDSTATES PATENTS 2,195,491 M archev Apr. 2, 1940 2,768,578 Park et al Oct.30, 1956 2,910,939

Mosegaard Nov. 3, 1959

